An impregnated tubular article

ABSTRACT

A MULTI-PLY TUBULAR BODY OF FIBROUS MATERIAL WHEREIN CONTINUOUS PORTIONS ADJACENT TO AND INCLUDING THE INNER SURFACE, THE OUTER SURFACE AND THE END SURFACES ARE IMPREGNATED WITH A SNYTHETIC RESINOUS MATERIAL WHICH COMPLETELY ENCOMPASS AN INTERNAL UNIMPREGNATED SIDEWALL PORTION EXTENDING THROUGHOUT THE MAJOR PORTION OF THE LENGTH AND THICKNESS OF THE TUBULAR BODY SIDEWALL.

United States Patent lnventors Appl. No.

Filed Patented Assignee McCleer-y I. Cunningham;

Auburn Woods, Jr; Charles K. Dunlap, Jr, lhrtzville, S.C.

May 20, 1968 June 28, 1971 Sonoco Products Company IMPREGNATED TUBULAR ARTICLE 3 Claims, 4 Drawing Fig 3.

US. Cl 138/144 Int. Cl. F16l 9/14 Fielrlofsenrdl 138/144 [56] References Cited UNITED STATES PATENTS 2,291,838 8/1942 Shoan 138/144X 3,008,493 ll/l96l Roe 138/146 3,451,433 6/1969 Cunningham et al. 138/144 3,468,733 9/1969 Dunlap et a1. 156/190 Primary Examiner-Louis K. Rimrodt Al!0meyC. Gordon McBride ABSTRACT: A multi-ply tubular body of fibrous material wherein continuous portions adjacent to and including the inner surface, the outer surface and the end surfaces are impregnated with a synthetic resinous material which completely encompass an internal unimpregnated sidewall portion extending throuylout the major portion of the length and v thickness of the tubular body sidewall.

PATENTEU JUH28 1971 INVENTOR H 7 0 W W fi M m/zA DD/ w k A w 1 aus 4 R A YUL B M M L 0 w M IMPREGNA'IIID TUBULAR ARTICLE This invention relates to a tubular article and more particularly to a paper tube impregnated with a synthetic resinous material.

Tubes made from fibrous material such as paper are generally formed by spirally or convolutely winding a plurality of strips of paper in overlying relationship with adhesive therebetween to form a multi-ply paper tube. In order to increase the strength and resistance to moisture of such paper tubes as well as to form a relatively hard outer surface on these tubes, the tubes may be impregnated with a suitable impregnant such as a synthetic resinous material. The impregnation of such tubes, generally carried out by immersing such tubes in a bath of impregnating material. is performed by completely impregnating the tube to provide a hard, heavy, and rigid tubular article. In order tocompletely impregnate the tube, the impregnation must, of necessity, be extended for a relatively long period of time lowering to an undesirable extent the production rate for such tubular articles. Furthermore, the complete impregnation of such paper tubes adds considerably to the cost of the resulting product due to the relatively expensive impregnating medium commonly used. In addition, the amount of impregnant required for complete impregnation of the tube adds considerably to the weight of the tube as well as imparting to the tube a high degree of rigidity which in at least some applications may be undesirable.

Accordingly, a primary object of this invention is to provide a new and novel multi-ply tube of fibrous material impregnated with a synthetic resinous material.

Another object of this invention is to provide a new and novel multi-ply paper tube impregnated with a resinous material which may be formed at a high rate of production and which requires a minimum of impregnatipg material.

A further object of this invention is to provide a new and novel multi-ply paper tube impregnated with a synthetic resinous material which is light weight and inexpensive in construction, which has a limited degree of flexibility, and which provides all of the desirable qualities of a completely impregnated paper tube. 1

Still another object of this invention isto provide a new and novel method of impregnating a multi-ply paper tube with a synthetic resinous material. i

A further object of this invention is to provide a new and novelmethod of impregnating multi-ply paper tube with a synthetic resinous material which may be carried out in a simple and easy manner at a high production rate using conventional apparatus and which utilizes readily available materials.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawing.

The objects stated above and other related objects of this invention are accomplished by the provision of a multi-ply tubular body of fibrous material having a sidewall. The tubular body sidewall has an inner surface, an outer surface, and end surfaces and continuous portions of the tubular body sidewall adjacent to and including the inner surface, the outer surface and theend surfaces are impregnated with a synthetic resinous material with the impregnated sidewall portions completely encompassing an internal unimpregnated sidewall portion extending, throughout the major portion of the length and thickness of the tubular body sidewall. I

The novel features which are believed to be characteristic of the invention are set forth particularity in the appended claims. The invention itself, however, as to its organization and method of operation may be best understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIG. I is a perspective view of a tubular article formed in accordance with the invention;

FIG. 2 is an enlarged sectional view taken substantially long line 2-2 of FIG. 1;

FIG. 3 is a sectional view of apparatus for carrying out the method of the invention; and

FIG. 4 is a perspective view of the tubular article of FIG. 1 together with apparatus by means of which the method of the invention may be carried out.

Referring now to the drawings and to FIGS. 1, 2 in particular, there is shown a tubular article formed in accordance with the invention which has been designated generally by the letter T. The tubular article T includes a Inulti-ply tubular body 10 of fibrous material such as paper having a sidewall 11. In the preferred form, the tubular body 10 is formed by spirally winding a plurality of strips of paper in overlapping relationship with adhesive therebetween in the well-known manner to form a spirally wound paper tube having a spiral inner seam 12 and a spiral outer seam 13 as shown best in FIGS. 1, 2. The tubular body sidewall 11 is formed from a plurality of paper plies 14 as shown best in FIG. 2 and includes an inner surface 16, an outer surface 17 and end surfaces l8, 19.

The tubular body sidewall has continuous portions adjacent to and including the inner surface 16, the outer surface-l7 and the end surfaces 18, 19 impregnated with a suitable synthetic resinous material such as a polyester resin. More specifically, these continuous portions are identified in FIG. 2 as portions 21, 22, 23, 24 and include the tubular body sidewall inner surface 16, outer surface 17, and end surfaces l8, l9 respectively. The impregnated sidewall portions 21-2 4 completely encompass an internal unimpregnated sidewall portion 26 which extends throughout the major portion of the length and thickness of the tubular body sidewall 11 as shown.

The impregnation of the sidewall 11 may be carried out in any suitable apparatus such as the apparatus of FIG. 3 in which the tubular body 10 is immersed. The impregnating apparatus of FIG. 3 is shown as a pressure vessel of conventional construction and is designated generally by the letter P. The pressure vessel P includes a casing 28 defining an interior 29 in which a plurality of tubular bodies 10 are stacked in any suitable manner. Preferably a ledge 31 is positioned within the vessel interior 29 on which the tubular bodies 10 are supported in stacked relationship and a lid 32 together with legclamping means 33 are provided for closing and sealing the casing 28.

The interior 29 of the pressure vessel P is arranged to be connected in communication with a vacuum source 34 by suitable means such as a conduit 36 through a valve 37. The interior 29 of the pressure vessel P is filled with a suitable impregnating material such as a polyester resin to provide a bath 38 in which the tubular bodies 10 are immersed.

In carrying out the impregnating operation of the invention, a plurality of tubular bodies 10 are stacked on the ledge 31 of the pressure vessel P which has been filled with the impregnating fluid 38 as shown in FIG. 3. The lid 32 is then clamped in the closing position of FIG. 3 by the clamping means 33. The interior of the casing 28 is then placed in communication with the source of vacuum 34 by means of valve 37 so as to. subject the bath 38 and the tubular bodies 10 immersed therein to a vacuum for a predetermined period of time. Preferably, the vacuum is imposed on the bath 38 for approximately 15 minutes at approximately 28 inches of mercury. As is well known, the application of such a vacuum to the bodies 10 removes substantially all of the air and moisture contained in the tubular bodies 10. After'the air and moisture have been evacuated from the bodies 10, the valve 37 is then closed and the tubular bodies 10 are immersed in the bath 29 and then permitted to absorb the impregnating medium of the bath for a predetermined period of time. Preferably, this absorption step is carried out at atmospheric pressure and for a period of approximately 15 minutes.

The novel method of the invention may be carried out on any size tubular body 10 and by way of example, a tubular body 10 having a length of approximately 10 inches and a wall thickness of approximately 0.300 inch may be utilized in accomplishing the novel results of the invention. If desired, the outer surface 14 of the impregnated tubular body 10 may be subjected to a grinding operation to produce a smooth, uniform outer surface 17. As shown in FIG. 4, such a grinding operation may be carried out using any suitable grinding means such as an abrasive belt 41 supported on rollers 42, 43 and driven by suitable means (not shown).

With the novel construction of the invention, there has been provided a multi-ply spirally wound paper tube which has been impregnated with a synthetic resinous material such as a polyester resin which provides all of the strength, durability and other advantages available in a completely impregnated tube without the disadvantages of high cost and weight and extreme rigidity common to such a completely impregnated paper tube. Not only is the tubular article of the invention capable of resisting the destructive forcesto which such a tube is exposed during use but the tube of the invention is provided with a certain degree of flexibility so that the effect of these destructive forces is further minimized. The impregnation of the tubular body of the invention may be carried out using conventional apparatus but at an extremely rapid rate so as to further reduce the initial cost of such tubes. Furthermore, the outer surface of the tube of the invention may be ground by suitable grinding means so as to provide a smooth, uniform outer surface on the tube.

Whilethere has been described what at present is considered to be the preferred embodiment of the invention, it

will be understood by those skilled in the art that various changes and modifications may be made without departing from the invention and, therefore, it is the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. A tubular article comprising, in combination, a multi-ply tubular body of fibrous material having a sidewall, said tubular body sidewall having an inner surface, an outer surface and end surfaces, said tubular body sidewall having continuous portions adjacent to and including said inner surface, said outer surface and said end surfaces impregnated with a synthetic resinous material, said impregnated sidewall and end surface portions completely encompassing an internal unimpregnated sidewall portion extending throughout the major portion of the length and thickness of said tubular body sidewall.

2. A tubular article in accordance with claim 1 wherein said tubular body is provided with a smooth, uniform outer surface.

3. A tubular article in accordance with claim 1 wherein said tubular body is a spirally wound, multi-ply paper tube. 

